My dictionary has morhwch as a translation for dolphin, but Duo doesn't accept it. Do people not use the word anymore? It accepts morgi for shark, so is that still in more common use, or what? I find it a bit sad that they only teach the "English" word though, especially because the etymologies for the Welsh words are so cool!
Whale 
Morfil "sea beast"
Shark Morgi "sea dog"
Dolphin Morhwch "sea pig"
Porpoise Llamhidydd "leaper"
also interesting that it's that way round for dolphins and poiposes because I would've said dolphins leap out of the water more, and porpoises more resemble pigs...
Learning: 
Future?: 
